Instead of trying to invent a better mousetrap for the umpteenth time, why don't they focus on consolidating, editing, re-presenting logically and balancing a prior edition? Imagine a balanced, unified, streamlined AD&D or 3E, with all the splat designed to work together and "knowing the existence of each other" from the start. In other words, an actual new edition rather than a whole new game masquerading as a new edition.
No-one else can do this but WOTC. It's a headscratcher why they just sit on this IP goldmine and release yrthaks, digesters, razorfang bloodthunderers and the like in place of better monsters that are in their inventory from prior editions. Same with spells and magic items. The "turns victim inside out and sends them through hell" spell sounds like it's from another game in some Hellraiser genre, rather than D&D. Why bother with flavor like that when there's better ideas already around?
We got a hint of what this can be like with Hackmaster 4E; because the spells and monsters were released in one big chunk, rather than over many years, the spell components that could be drawn from monster parts was all organised, making it look like a unified game in this respect rather than a hodge-podge.
In other words, maybe take off the rules mechanic designer cap, put on the editor cap, and actually produce a new edition of D&D rather than a new game, complete with new mechanics, obligatory new cosmology and new experimental critters in place of classic favorites.